De novo methylation of tumour suppressor genes CDKN2A and CDKN2B is a rare finding in B-cell chronic lymphocytic leukaemia

De novo methylation of the 5'CpG island has been recently reported as an alternative mechanism of inactivation for the tumour suppressor genes CDKN2A and CDKN2B. We examined CDKN2A methylation status at diagnosis in 42 B-cell chronic lymphocytic leukaemia (CLL) patients, in 19 cases the CDKN2B methylation status was also analysed. No homozygous CDKN2A/2B deletion was detected, but four patients (9%) displayed an aberrant CDKN2A methylation status and only one had hypermethylated CDKN2B. De novo methylation was associated with silencing of gene expression. These results confirm that CDKN2A/2B inactivation by deletion is a rare event in CLL and suggest that aberrant methylation could be an alternative way of inactivation very rarely involved in the development of some CLL.     

Alterations of the RB tumour suppressor gene in hepatocellular carcinoma and hepatoblastoma cell lines in association with abnormal p53 expression

SUMMARY. Alterations in the expression of the RB tumour suppressor gene were found by Western immunoblot in three of seven hepatocellular carcinoma and hepatoblastoma cell lines. Abnormalities were detected by single-strand conformation polymorphism (SSCP) within exons 17–21 in RB cDNA from two of these three cell lines and within exons 20–21 in the third cell line. In these three cell lines with abnormal RB expression, abnormal expression of the p53 tumour suppressor gene was also found, apparently the product of a mutant gene. Thus, mutations within the RB gene (or splice-site mutations with exon-skipping) and apparent mutations of the p53 gene together may have contributed to the development of three of these tumours or to the establishment of these cell lines.     

Low expression of the putative tumour suppressor gene gravin in chronic myeloid leukaemia, myelodysplastic syndromes and acute myeloid leukaemia

The putative tumour suppressor gene gravin is down-regulated in several solid tumours and is implicated in tumorigenesis. We have evaluated the expression levels of the gravin gene in the CD34(+)/blast cells of a range of myeloid malignancies as compared with controls using real-time quantitative polymerase chain reaction (PCR). Gravin was markedly down-regulated in 41 of 41 patients with acute myeloid leukaemia (AML), nine of 10 patients with myelodysplastic syndromes (MDS) and 33 of 33 patients with chronic myeloid leukaemia (CML), of whom 24 were in blast crisis (BC). We have shown that gravin is consistently down-regulated in the CD34(+)/blast cells of myeloid malignancies and may play a role in the molecular pathogenesis of these disorders.     

Deletion in chromosome 11 and Bcl-1/Cyclin D1 alterations are independently associated with the development of uterine cervical carcinoma

Purpose The aim of this study was to understand whether there is any association between specific deleted regions in chromosome 11 (chr.11) and alteration (amplification/rearrangement) of Bcl-1/Cyclin D1 locus, located at 11q13, in uterine cervical carcinoma (CA-CX).Methods The deletion mapping of chr.11 was studied using 17 highly polymorphic microsatellite markers in 65 primary uterine cervical lesions. The Bcl-1/Cyclin D1 alterations were analyzed by Southern blot and/or polymerase chain reaction (PCR) method in respective cervical lesions.Results Chr.11 deletion was found to be significantly associated with progression of CA-CX. High frequency (48–65%) of deletion was found in 11p15.5 (D1), 11q22.3–23.1(D2), and 11q23.3–24.1(D3) regions and significant association was seen among deletions in D2 and D3 regions. Bcl-1/Cyclin D1 locus alteration was observed in overall 27% cervical lesions. Co-amplification of Bcl-1/Cyclin D1 locus was seen in 10% samples. However, no association was found between the deleted regions and Bcl-1/Cyclin D1 locus alterations.Conclusions Our study suggests that there is no co-operativity between the deleted regions (D1- D3) in chr.11 and Bcl-1/Cyclin D1 alterations, but these alterations may provide cumulative effect in progression of the tumor. The D1–D3 regions may harbor candidate tumor suppressor gene(s) (TSGs) associated with the development of CA-CX.Financial support for this work was provided by grant [no. 27 (0111)/00/EMR-II] from CSIR, Govt. of India to C.K. Panda and CSIR -JRF/NET Fellowship grant (no. 9/30 (026)/2002- EMR-I) to R.K. Singh     

Biochemical diagnosis, localization and management of pheochromocytoma: focus on multiple endocrine neoplasia type 2 in relation to other hereditary syndromes and sporadic forms of the tumour

Approximately 50% of patients with multiple endocrine neoplasia (MEN) 2A or 2B develop pheochromocytoma. These tumours are almost exclusively benign and localized in the adrenal glands. About one-third are bilateral at initial diagnosis. Amongst patients with pheochromocytoma, those with MEN 2A have subtler symptoms compared to those with sporadic disease. Since pheochromocytomas in patients with MEN 2 often secrete catecholamines episodically (but metabolize them continuously to metanephrines), the first choice for biochemical diagnosis is the measurement of free metanephrines in plasma, with urinary fractionated metanephrines being the second choice. In patients with pheochromocytomas that produce exclusively normetanephrine, MEN 2 can be excluded. In patients with biochemically proven MEN 2-related pheochromocytoma, anatomical imaging of the adrenals (with either computerized tomography or magnetic resonance) should be obtained next. Functional imaging with specific ligands (e.g. scintigraphy with [(123)I]-metaiodobenzylguanidine or, if available, positron emission tomography with [(18)F]-fluorodopamine, [(18)F]-dihydroxyphenylalanine, [(11)C]-adrenaline or [(11)C]-hydroxyephedrine) may then be particularly useful in patients with distorted anatomy from previous surgery, in cases of equivocal biochemical data despite high clinical suspicion for a tumour, to rule out multifocal disease, or where there is suspicion of metastatic disease (e.g. tumours larger than 5 cm). Laparoscopic surgery is the treatment of choice and subtotal (cortical-sparing) adrenalectomy is the procedure of choice in bilateral pheochromocytomas.     

Identification of a novel missense mutation in the TPM1 gene via exome sequencing in a Chinese family with dilated cardiomyopathy: A case report and literature review

Rationale:Dilated cardiomyopathy (DCM) is a cardiovascular disorder characterized by consecutive ventricular dilation and contractile dysfunction, often leading to congestive heart failure. DCM type 1Y (DCM1Y) is caused by a mutation in the TPM1 (tropomyosin 1) gene. To date, about thirty TPM1 gene mutations have been reported to be related to DCM1Y. However, mutational screening of the TPM1 gene is still far from being complete. Identification of TPM1 mutation is particularly important in the diagnosis of DCM1Y and will give more insights into the molecular pathogenesis of DCM1Y.Patient concerns:A Chinese Han family with DCM phenotypes was examined.Diagnosis:A novel missense mutation, c.340G > C in exon 3 of the TPM1 gene, was identified.Interventions:Next-generation sequencing (NGS) of DNA samples was performed to detect the gene mutation in the proband, which was confirmed by Sanger sequencing.Outcomes:This novel heterozygous mutation results in the substitution of glutamic acid with glutamine (p.E114Q). Based on this finding and clinical manifestations, a final diagnosis of DCM1Y was made.Lessons:We present evidence that p.E114Q mutation represents a novel TPM1 mutation in a Chinese Han family with DCM. Our data expand the mutation spectrum of the TPM1 gene and may facilitate the clinical diagnosis of DCM1Y.     

Haemochromatosis: understanding the mechanism of disease and implications for diagnosis and patient management following the recent cloning of novel genes involved in iron metabolism

Haemochromatosis, a common recessive genetic disorder in people of Northern European descent, is an iron storage disorder characterized by excessive hepatic iron accumulation resulting from disruption of the regulation of intestinal iron absorption. The identification of novel genes involved in the control of iron absorption from the diet has allowed improved understanding of iron metabolism in health and disease. In particular, the identification of the haemochromatosis gene (HFE) and more recently the transferrin receptor 2 gene (TfR2) together with the specific mutations in these genes which result in hepatic iron overload, has enhanced our understanding of the pathophysiology of haemochromatosis. However, because of the wide variation in phenotypic expression of the disease, there now exists a considerable challenge to diagnosis and patient management.     

A novel single base deletion in the LDLR gene (211delG): Effect on serum lipid profiles and the influence of other genetic polymorphisms in the ACE, APOE and APOB genes

A single base deletion (211delG) in the low density lipoprotein receptor (LDLR) gene was shown to cause familial hypercholesterolaemia (FH) in a large family from Northern Ireland. Twenty-four of 52 family members tested had this mutation, 13 of which were newly diagnosed. Mutation-positive individuals had significantly higher mean total-cholesterol (TC) and LDL-cholesterol (LDL-C) than those without 211delG. LDL-C was a more accurate indicator of disease status than TC. When TC levels alone were considered, in individuals over 16 years, a false negative rate (TC < 7.5 mmol/l) of 40% was found; however, this fell to 13% based on inclusion of LDL-C levels. Individuals with coronary artery disease (CAD) had significantly higher TC levels than those without CAD and tended to have tendinous xanthomas (TX) and corneal arcus (CA). Genetic polymorphisms in the angiotensin converting enzyme (ACE) and apolipoprotein (apo) B genes did not appear to be associated with lipid levels or with the clinical severity of the disease; however, the apo E 4 allele did show a lipid-raising effect in individuals with the mutation.